1. Field of the Invention
The present invention is generally related to network-based content delivery systems and, in particular, to a streaming media content delivery system supporting multiple, concurrent, peer-based sources of multimedia content accessible subject to central mediation.
2. Description of the Related Art
The desire for high-quality, on-demand delivery of streaming multimedia and other rich digital content is a principal driving force in the continued development of the broadband Internet infrastructure. Indeed, with the growth of broadband connections, the number, scale, and diversity of multimedia content servers has rapidly increased. Streaming audio and video files, including entertainment, news broadcasts, and instructional programming are now sourced by a variety of mainstream Internet sites. Content delivery through streaming media is broadly recognized as one of the fastest growing technologies related to the Internet.
Despite the growth in interest and use, conventional content streaming systems have not been cost-effective or particularly reliable in delivering high-quality content. Streaming media content, including in particular high-quality audio and video, is naturally bandwidth intensive and fundamentally sensitive to varying delivery latencies. Whether due to transient transport overloads, functional interruptions in the network infrastructure, or bandwidth limitations of a content source site, the result is uniformly perceived by a recipient as a reduction in the quality of service of the content source site.
Because of the open and shared nature of the Internet, few practical mechanisms can ensure the uninterrupted delivery of broadband content, typically consisting of multi-megabyte files, over the entire delivery path from a source site to a recipient. Known schemes include the use of network edge caches distributed at strategic locations within the network infrastructure controlled by an individual service provider. These network edge caches can be operated to significantly reduce the network traffic through the local network space of the individual service provider. Large edge caches are naturally required to store any significant amount of streaming media content. Implementing a useful number of adequately scaled, geographically distributed edge caches requires a large capital infrastructure investment.
Quality of service issues within the domain of individual content source sites are relatively easier to manage. Over the past few years, highly scaled, geographically distributed and even multiply redundant content source system architectures have been developed. Conventionally, these very large-scale systems are considered a baseline requirement to ensure a consistent high quality of service from the source sites. These sites typically employ large-scale server farms, hosting extensive libraries of archived multimedia content, that cumulatively provide sufficient throughput to enable real-time responsiveness and continuous on-demand delivery. Very high-bandwidth Internet connections with sufficient capacity to accommodate peak-demand content access requirements are also required.
Unfortunately, conventional content delivery networks, including fully scaled content server systems and extensive edge cache networks, have not proven adequate to broadly ensure a high quality of service to all potential users of the systems. Ultimately, any media content must be delivered as an effectively continuous stream of multimedia data to the recipient computer. The continuity of the stream must remain within the buffer length tolerance supported by the media player on the recipient computer. Transient bandwidth bottlenecks can certainly occur anywhere beyond the scope of a conventional content delivery network. Bottlenecks and delivery latencies can occur even within the network, particularly whenever the stream data is not immediately available in a locally accessible edge cache. Such bottlenecks in the Internet infrastructure are unfortunately both common and unpredictable.
Transient bandwidth bottlenecks can also occur in within the content server system itself. The rate of content access requests is highly variable with unpredictable demand peaks. Whenever the access rate exceeds the capabilities of the content server system, connection requests, including ongoing streaming data transfers, are dropped or delayed. Whether due to network or server bottlenecks, the resulting latencies and gaps in the delivery of stream data packets ultimately to the recipient are uniformly seen as source-site quality of service failures.
Expanding the conventional content distribution networks to prevent significant transient bandwidth bottlenecks is generally recognized as not practical. Due to the size and diversity of the Internet and the growing demands for streaming content delivery, significantly expanding the edge cache network coverage and the capacity of all included edge caches and streaming media source sites is simply not cost-effective. Furthermore, the costs associated with high-bandwidth Internet access and server throughput grow proportional to peak access demands, which is disproportionately greater than the growth of average access demands. Conventionally, a minimum of 50 percent additional access and server bandwidth is required, if not more, to meet peak bandwidth requirements. This additional bandwidth, however, is unused typically in excess of 90 percent of the time. The capital and operating cost of this additional bandwidth is therefore not directly recoverable. Consequently, content sites and the content delivery network operators have been severely limited in being able to consistently and profitably deliver streaming media content with a high quality of service.
Consequently, there is a clear need for a content delivery network architecture that can reliably provide a high quality of service to content stream recipients and that is cost-effective to operate.